Portion of a tractor



FIG. 1 is a right side view of a portion of a tractor showing our new design;

FIG. 2 is a left side view thereof;

FIG. 3 is a front view thereof;

FIG. 4 is an upper right front perspective view thereof;

FIG. 5 is an enlarged front view thereof; and,

FIG. 6 is an enlarged upper right front perspective view thereof.

The portions of FIGS. 1-6 shown in coarse dot pattern and outlined in dashed lines form no part of the claimed design.

A bottom view is omitted because it is plain and unornamental and forms no part of the subject matter of the claimed design. 

CLAIM The ornamental design for a portion of a tractor, as shown and described. 